Questions in regards documents needed for Q2 visa

My wife is a UK citizen but was chinese previously before naturalization in UK. We are currently residing in Malaysia and she wants to know if we can apply in Kuala Lumpur for a Q2 type and if yes what documents over and above the ones pointed out in your article. She has since lost her original Chinese passport due to our moving from one country to the next but we might have an old scan of her passport. Do the Chinese authorities need such documents? Can she apply in Hong Kong as she was a Shenzhen citizen before?
Thanks
Chris Chapman